Hydraulic elevator



Sept. 26, 1944. F. HYMANS HYDRAULIC ELEVATOR Filed Aug. 14, 1943 2Sheets-Sheet 1 INVENTOR ATTORNEY PM H BY I W F. HYMANS HYDRAUL I CELEVATOR Sept. 26, 1944.

Filed Aug. 14, 1943 2 Sheets-Sheet 2 1'; Z WW INVENTOR BY mu! .44All- 1ATTORNEY Patented Sept. 26, 1944 UNITED STATES PATENT OFFICE HYDRAULICELEVATOR Frederick Hymans, Larchmont, N. Y., assignor to Otis ElevatorCompany, New York, N. Y., a corporation of New Jersey Application August14, 1943, Serial No..498,904

6 Claims.

The invention relates to hydraulic elevators.

There are certain advantages in hydraulic elevators, especially for lowrise installations. Such elevators arev particularly suitable forinstallation on ships and in certain categories are required. In certaintype ships such as naval vessels, counterweights for the cars are notpermitted, thereby adding to the power required to operate th elevator.For exceptionally heavy duties on ships of this character, as forexample elevators for carrying airplanes on airplane carriers, the powerrequired to operate the elevator is considerable. Also, speed ofoperation is important so-that it is desirable to operate the car at afast speed between the transfer decks and at a slow speed preparatory tostopping the car. Furthermore, it is important that the car platform bekept level with the transfer decks in order that the transfer of theplanes may be readily made and, in the case of the upper transfer orflight deck, in the event that an airplane should land on this deck.

It is the principal object of the invention to provide a hydraulicelevator in which the car may be operated at a fast speed betweenlandings and at a slow speed as it approaches the landing at which astop is to be made, in which the car platform is maintained level withthe landings when stopped and in which the power required to operate theelevator is minimized.

In carrying out the invention, according to the embodiment which will bedescribed, a hydraulic counterpoise is provided for the elevator car inthe form of a tank containing fluid under pressure. Pumps are providedbetween the tank and the lifting cylinder for effecting fluid transfertherebetween. One of these pumps is of relatively small capacity and isutilized for operating the elevator car at a slow speed preparatory tostopping. The invention will be described as applied to an installationin which the elevator platform is utilized to transfer airplanes betweena hangar deck and a flight deck. To maintain the platform level with theflight deck an accumulator is employed in conjunction with the smallpump to hold the platform against stops associated with the flight deck.

Features and advantages of the invention will be apparent from the abovestatements, the description which follows and appended claims.

In the drawings:

Figure l is a diagrammatic representation of a hydraulic elevatorinstallation embodying the invention; and

Figure 2 is a schematic wiring diagram of a simple electrical controlsystem for the elevator, illustrating interconnections for the variouselevator control devices.

Referring first to Figure '1, the elevator installation illustrated isone in which the elevator platform i0 is utilized to carry airplanesfrom the hangar deck ll of an airplane carrier to the flight deck l2 andto return them from the flight deck to the hangar deck. Also theelevator is illustrated as of the plunger type. The plunger i3 issecured at the top to the platform In from which it extends downwardlyinto the cylinder M through a stufling box IE. Extensions I6 areprovided on the platform for engaging the bottom of the flight deckwhich forms stops to align the platform with the flight deck. Pads I'lare provided on the bottom of the platform which engage stops i8 belowthe level of the hangar deck to align the platform with the hangar deck.

Cylinder I4 is connected to a reservoir 20. One connecting path is byway of pipe 2| through a poppet valve 22 and the main pump 23 to anotherpipe 24 connected to tank 20 near the bottom thereof. The pump isillustrated as a gear pump driven by an electric motor 25 and providedwith an electromechanical brake 26 for bringing the pump to a stop. Thepoppet valve is illustrated as of the balanced pressure type, operatedby an electromagnet 2! and biased to closed position by a spring 28. Thepoppet valve is bypassed by a check valve 30 by way of pipes 3i and 32.The check valve is illustrated as of the hinged type.

Another connecting path between the cylinder and the reservoir is by wayof pipes 2|, 3| and 33 through a poppet valve 34 and auxiliary pump 35to pipe 24. Pump 35 may also be a gear pump driven by an electric motor36 and provided with an electromechanical brake 31. The poppet valve maybe of the same type as valve 22, its operating electromagnet beingdesignated 40. It also is by-passed, the by-pass being by way of pipe 38through a check valve 4| which may be of the hinged type.

The reservoir 20 is illustrated as in the form of a vertical tank,partially filled with liquid 42, such as oil, for operating theelevator. Above the liquid level is air 43 under pressure. The pipe 44indicates a source of air supply for providing the desired pressure inthe tank.

The pipe 3! is connected to an accumulator 45. This accumulator isillustrated as in the form of a cylinder '46 to which pipe 3| isconnected and having a plunger 41 operating therein.- The end down to alow speed determined by the capacity of the auxiliary pump.

As-the platform reaches the level of the flight deck its extensions llengage the bottom of the flight deck to bring the platform to a stop.The

auxiliary pump continues in operation, however,

tending between them.- It is to be understood that the cylinder andreservoir are provided with suitable stumng boxes; not shown.

The main pump 23 is provided with a relief valve 58. This valve isillustrated as in the form of a valve member I biased to closed positionby a spring I8. Thevalve is illustrated as arranged in a pipe '1connecting pipe 2| adjacent the'main pump to reservoir 2| at the bottomthereof. A' similar relief valve ll is'provided for\ auxiliary pump 35and is arranged in a pipe is connecting pipe 33 adjacent the auxiliarypump to the reservoir at the bottom thereof. Instead of 'extending tothe reservoir... pipes 51 and Ill may discharge into open tanks. Arelief .valve II is provided for reservoir 20.

Referring now also to Figure 2, push buttons are illustrated forexercising manual control of the operation of the elevator. These'pushbutsupplying oil to the cylinder 46 of the accumulator. The oil thussupplied forces plunger '41 outwardly from the cylinder and thus plungerll farther into reservoir I! against the existing air pressure. When theaccumulator plunger 41 has been moved outwardly a-certain amount so thata considerable quantity of oil has accumulated in cylinder ll, cam '|icauses opening of switch II to'break the circuit for the coil oi'switchH to cause deenergization of motor as and the release coil /'of brake 31.to bring the auxiliary motor to a' stop. The air pressure in reservoir50 is suflicient to maintain enough pressure in cylinder H to hold theplatform against the flight deck even when a plane lands on theplatform.

- This is the condition of the system as illustrated in Figure 1. Asleakage of 'oil takes place in the tons are arranged in the elevatorplatform aha-- the platform atany point. Blowing down of the elevator asit nears the flight deck is effected by I means of a switch I operatedby a cam I! carried by the platform. A similar switch I1 is operated bythe cam to slow down the platform as it nears the hangar deck. Cam l6operates a second switch II as the platform reachesthe hanger deck tostop the platform. A stem "extends main cylinder is plunger 41 is forcedback into cylinder M by the air pressure in reservoir ll, causing thereclosing of switch 12. This reestablishes the circuit for the coil ofswitch H which operates to restart the auxiliary pump. This renews theoil in the accumulator, and this oper-. ation is repeated so long as theplatform remains at the flight deck, thereby assuring the platform beingmaintained level with the flight deck at all times,

To lower the platform, do'wn button II is pressed. This completes thecircuit for the coil of-switch'D whichoperates to causev release ofelectromechanical brake l and to cause current to be supplied to motorII for rotation clockwise as viewed in Figure 1. At the same time switchupwardly from plunger 41 and has a cam 'II' on 40 D causes energizationof operating magnet 21 the upp r end thereof for operating a switch-I2to stop the auxiliary pump is when suflicient oil has been forced intocylinder 40 to move plunger 41 downri'va'rdly far enough for can II tooperate switch] Assume that the platformis at deer and that itis desiredto'raise it to the flight deck.

The up button O2 ispressed. buttons-eta through electrom netic switch U-to cause env ergisationof the release coil for-the, electrome-\chanical-brake fl to'release the brake and to cause'current to besupplied to motor 25 for rotaof poppet valve 22 to open this valve. Themain pump being rotated in a direction to return oil to reservoir 2|,oil flows from cylinder It by way of pipe 2|, through poppet valve 22(check valve II preventing the flow of oil by way of pipe I!) pipe It tothe bottom of reservoir 20. Assuming that, asillustrated in Figure 2,down button 08 also operation 01E switch D', brake 31 is tioncounterclockwise, as viewed in Figure 1. This causes operation of themain pump to force 011 by way of pipe 2|, pipe 82 through check valvell, pipe ll,'and thence again to'pipe and into cylinder 'II. This forcesplunger l3 upwardly to raise platform II. It will be assumed that asillustrated in the wiring diagram the control is arranged so that button'82. also acts through electromagnetic switch U to cause energization ofthe release coil of brake 31 and to cause-current to be supplied tomotor I! to operate auxiliary pump it to force oil by way of pipe 38,pipe "through check valve ll, pipe II and pipell to stop .the main pump.The auxiliary pump 35,

released-and motor It is energized for clockwise so'that oil-also flowsby way of'plpeli valve 3, opened as the result of the eriergiaation. ofits operating electromagnet 4| along with energisation of motor II. tothe reservoir.

.As the-platform hangar'deck, cam

. u opens switch s1 which breaks the circuit for the coil of switch I),deener'gising electromagnet 2I, motor It and the releaseooil for brake2|. Thu the main pump is'stopp d andpopp t valve 22 is closed. The a x apump continues in operation, however, so that oil is returned in reducedvolume from the cylinder to the reservoir II. This slows down theplatform to a low speed. Just before the pads ll engage stops ll,

' cam ll opens switch ll which breaks the circuit for thecoil of switchD, deenergizing motor 00 and the release coil of brake 81 and the brakeis applied to bring the auxiliary pump to a stop. At the same timepoppet valve 34 closes. It is to be understood that suflicient timing isprovided, as by pro d s a condenser in parallel to the coil ofswitch Dto delay the dropping out of electromagnetic switching mechanismhowever, operates to supply oil in reduced'volume to the cylinder. As aresult the platform is slowed controlled by switch II, to enable thecontinued operation of the auxiliary pump suflieient to bring pads llagainst the stops and thus align the platform with the hangar deck. 4

Pressure of the air in reservoir II is such that the pressure exerted bythe oil in cylinder ll is somewhat less than the weight of plunger I3and unloaded platform It and apparatus carried thereby. when the pumpsare rotatedio raise the platform they act to build up the pressure to apoint sufficient to effect this operation. The capacity of the reservoiris such that the volume of air is large as compared with the change inthe volume of oil in moving the platform from one deck to another. Thusthe Variation in pressure in the reservoir in eifecting such movement isnot very great. The pressure in the reservoir may, therefore, beconsidered as a hydraulic counterpoise and the power of the pump drivingmotors need only be sumcient for handling the net load.

In lowering the platform, inasmuch as the pressure under the plunger isgreater than that in the reservoir, the pumps serve to regulate thespeed of descent. Since the speed of the elevator platform is inproportion to the speed of the pump driving motors there will be verylittle variation in the speed with or without load for each direc- Ition of travel.

The check valves 30 and ll act to prevent oil returning from thecylinder to the reservoir by way of the pumps when the pumps arestopped. The relief valves 53 and 58 open in case of abnormal pressure.If, for example, a pump should continue in operation to pump oil fromthe reservoir and thus build up pressure after the control mechanism hasacted to cause it to stop, its relief valve opens when the pressurereaches a certain point. Also should a pump be operated with a shut-offvalve (not shown) on the cylinder side of the pump closed, its reliefvalve opensto relieve the pressure.

While described as applied to an elevator utilized for raising andlowering airplanes it is to be understood that the invention may beapplied to other types of elevator installations. Also the invention maybe applied to other types of hydraulic lifting mechanism, as for examplehorizontal hydraulic engines with roping. While only two landings areillustrated, it is to be understood that the elevator may be arranged toserve more than two landings. Pumps of types other than gear pumps maybe utilized for effecting the transfer of oil from and to the reservoir.Two or more main pumps in parallel lines may be utilized instead of thesingle pump illustrated in which event it would be preferred to haveseparate driving motors and brakes for each pump with separateelectromagnetic control switches therefor. In such an arrangement thesepumps could be cut off one at a time to slow down the platform in steps.Variations may be made in the construction of valves illustrated, itbeing understood that the valves shown are diagrammatic and are for thepurpose of illustrating the operation.

The accumulator I5 is an important feature of the invention, especiallyfor airplane elevators on carriers where it is important that theplatform be kept level with the flight deck and maintained so even underconditions where a plane should alight on th platform. However, the

construction of the accumulator may be varied, it being understood thatthe arrangement shown is diagrammatic and for the purpose ofillustrating the operation of the invention.

As many changes could be made in the above construction and manyapparently widely diiferent embodiments of this invention could be madewithout departing from the scope thereof,- it is intended that allmatter contained in the above description or shown in the accompanyindrawings shall be interpreted as illustrative and not in a limitingsense.

What is claimed is:

1 1. An airplane transporting elevator for an airplane carriercomprising; a platform serving a flight deck and a hangar deck; aplunger extending downwardly from the platform; a cylinder for saidplunger; a reservoir containing 011 and air under pressure above theoil; main pumping mechanism connected on one side to said cylinder andon the other side to said reservoir; auxiliary pumping mechanismconnectedon one side to said cylinder and on the other side to saidreservoir; means for causing operation of said pumping mechanisms totransfer 011 from the reservoir to said cylinder to raise said platform;means operable as the platform nears the flight deck to cause stoppingof the main pumping mechanism to slow down the platform; and means forstopping the platform when it becomes level with the flight deck.

2'. An airplane transporting elevator for an airplane carriercomprising; a platform serving a flight deck and a hangar deck; aplunger extending downwardly from the platform; a cylinder for saidplunger; a reservoir containing oil and air under pressure above the oilmain pumping mechanism connected on one side to said cylinder and on theother side to said reservoir; auxiliary pumping mechanism connected onone side to said cylinder and on the other side to said reservoir; meansfor causing operation of said pumping mechanisms to transfer oil fromthe reservoir to said cylinder to raise said platform; means operable asthe platform nears the flight deck to cause stopping of the main pumpingmechanism to slow down the platform; means for stopping the platformwhen it becomes level with the flight deck; an accumulator having achamber connected to said cylinder for storing oil under pressure uponoperation of the auxiliary pumping mechanism after the platform hasstopped; and means responsive to the volume of oil in said chamber tocause stopping of the auxiliary pumping mechanism when said oil in thechamber reaches a certain volume and to cause restarting of theauxiliary pumping mechanism when said oil in said chamber decreases tobelow said certain volume.

3. An airplane transporting elevator for an airplane carrier comprising;a platform serving a flight deck and a hangar deck; a plunger extendingdownwardly from the platform; a cylinder for said plunger; a reservoircontaining oil and air. under pressure above the oil; main pumpingmechanism connected on one side to said cylinder and on the other sideto said reservoir; auxiliary Du ping mechanism connected on one side tosaid cylinder and on the other side to said reservoir; means for causingoperation of said pumping mechanisms to transfer oil from the reservoirto said cylinder to raise said platform; means operable as the platformnears the flight deck to cause stopping of the main pumping mechanism toslow down the platform; means for stopping the platform when it becomeslevel with the flight deck; an accumulator having an oil chamberconnected to said cylinder and adapted in conjunction with saidauxiliary pumping mechanism to maintain sufiicient oil pressure in saidtending downw cylinder to hold said platform level with the flight deck,said accumulator also having an air chamber containing air underpressure against which oil is forced into said oil chamber; and meansoperable when the accumulator has received a certain amount of oil tocause stopping of the auxiliary pumping mechanism and also operable whenthe amount of oil in the accumulator has decreased a certain amount torestart the auxiliary pumping mechanism.

7 4. An airplane transporting elevator for an airplane carriercomprising; a platform serving a flight deck and a hangar deck; aplunger extending downwardly from the platform; a cylinder for saidplunger; a reservoir containing oil and air under pressure above theoil; main pumpingmechanism connected on one side to said cylinder and onthe other side to said reservoir; auxiliary pumping mechanism connectedon one side to said cylinder and on the other side to said reservoir;means for causing operation of said pumping mechanisms to transfer oilfrom the reservoir to said cylinder to raise said platform; meansoperable as the platform nears the flight deck to cause stopping of themain pumping mechanism to slow down the platform; means for stopping theplatform when it becomes level with the flight deck; an accumulatorhaving an oil chamber connected to said cylinder and adapted inconjunction with said auxiliary pumping mechanism to maintain suflicientoil pressure in said cylinder to hold said platform level with theflight deck, said accumulator also having an air chamber containing airunder pressure against which 011 is forced into said oil chamber; meansoperable when the accumulator has received a certain amount of oil tocause stopping of the auxiliary pumping mechanism and also operable whenthe amount of oil in the accumulator has decreased a certain amount torestart the auxiliary pumping meching mechanisms to transfer oil fromthe cylinder to said reservoir to lower said platform; means operable asthe platform nears the hangar deck to cause stopping of the main pumpingmechanism to slow down the platform; and means operable as the platformarrives at the hangar .deck to cause stopping of the auxiliary pumpingmechanism to stop the platform.

5. An' lane transporting elevator for an airplane c rrier comprising; aplatform serving a flight deck a hangar deck; a plunger exdly from theplatform; a cylinder for said plunger; a reservoir containing oil andair under pressure above the oil;- oil conductin: means between saidcylinder and said reservoir; additional 011 conducting means between.said cylinder and said reservoir; a main pump in the first namedconducting means;.an auxiliary pump in said additional conducting means;valve means for said main pump in said first named conducting meansbetween the pump and the cylinder; valve means for said auxiliary pumpin said additional conducting means between the v pump and the cylinder;means for causing operation of said pumps to transfer oil from thereservoir to said cylinder to raise said platform; means operable as theplatform nears the flight deck to cause stopping of the main pump toslow down the platform; means for stopping the platform when it becomeslevel with the flight deck;

I anism; means for causing operation of said pumpthe oil in saidcylinder under operation of the auxiliary pump after the platform hasstopped; means operable when the accumulator has acquired a certainamount of oil to cause stopping of the auxiliary pump and also operablewhenthe amount of oil in the accumulator has decreased a certain amountto restart the auxiliary pump: means for causing operation of said pumpsto transfer oil from the cylinder to said reservoir to lower saidplatform; means operable as the platform nears the hangar deck to causestopping of the main pump to slow down the platform: and means operableas the platform arrives at the hangar deck to cause stopping of theauxiliary pump to stop the platform.

6. An airplane transporting elevator for an airplane carrier comprising;a platform serving a flight deck and a hangar deck; a plunger extendingdownwardly from the platform; a cylinder for said plunger; a reservoircontaining a certain percentage by volume of oil and a larger percentageby volume of air under pressure above the oil; a main pump; a pipe lineconnecting one side of the pump to said cylinder and the other side ofthe pump to the oil containing portion of said reservoir; a p p t valvein said pipe line between the main pump and the cylinder; .a by-pass forthe poppet valve, said by-pass including a. check valve biased toprevent the flow of oil therethrough from the cylinder to the pump; anauxiliary pump; a pipe line connecting one side of the auxiliary pump tosaid cylinder and the other side to the oil containing portion of saidreservoir; a poppet valve in the last named pipe line between theauxiliary pump and the cylinder; a by-pass for the last named poppet(valve, said by-pass including a check valve biased to prevent the flowof oil therethrpugh from the cylinder to the pump; means for causingoperation of said pumps to build up the pressure of oil in said cylinderand transfer oil from the reservoir through the check valves to saidcylinder to raise said platform; means operable as the platform nearsthe flight deck to cause stopping of the main pump to slow down theplatform; means for stopping the platform when it becomes levelwith theflight deck; an accumulator connected tosaid cylinder and auxiliary pumpby the last named pipe line for building up the pressure of the oil insaid cylinder under operation of the auxiliary pump after the platformhas stopped; means operable when the accumulator has acquired a certainamount of oilto cause stopplns of the auxiliary pump and also operablewhen the. amount of oil in the accumulator has decreased a certainamount to restart the auxiliary pump; means for causing opening of saidpop et valves and operation of said pumps to transfer oil from thecylinder through'the poppet valves to said reservoir to lower saidplatform; means operable as the platform nears the hangar deck to causestoppinl of the main pump to slow down the platform and closing of thefirst named poppet valve; means operable as the platform arrives at thehangar deck to cause stopping ,of the auxiliary pump to stop theplatform and closing of the second named poppet .valve; and a pair ofrelief valves,

an accumulator connected to said cylinder and auxiliary pump forbuilding up the pressure of one for each pump, each relief valve beingon the cylinder sideof the pump for which it is provided.

' j r FREDERICK HYMANS.

